1. Field of the Invention
The invention relates to a method and system for delivering ground waters from under the bottom of water reservoirs for cooling equipment of onshore facilities.
2. Discussion of the Prior Art
A variety of industrial facilities generating or consuming electric energy necessarily use a cooling medium for providing proper functioning of the facilities' equipment. For example, steam power plants, typically generating electric energy, operate with a cooling medium such as a water/steam mixture, carried in an evaporator circuit of the steam power plant. The steam generated in the process expands to perform work in the steam turbine of the steam power plant and is subsequently fed to the condenser for producing a working medium. The latter is normally condensed by heat exchange with cooling water, which is fed directly to the condenser from a water reservoir, such as an ocean, sea, river or lake. This is known as an open cycle cooling system, or simply, open system.
Utilization of an open system operating with ambient surface waters for cooling purposes produces a variety of negative environmental impacts to the local receiving waters. For example, the massive volumes of water circulated through a large facility absorb heat from the condensers, typically raising the circulating cooling water temperatures 15 to 20 degrees (F) within seconds. Depending on the water demands of the power plant, cooling water discharged from the facility causes thermal plumes of ambient water in the vicinity of the powerplant or other heat producing industrial facility. During summer months these plumes are sufficiently hot to kill or stun fish and invertebrates.
Furthermore, small aquatic organisms are entrained by the pumped-in influent water. Entrainment is a term for the process of sweeping planktonic organisms, including eggs and larval forms through the cooling system of a powerplant. The organisms are subject to mechanical (pumping) stresses, thermal effects and injection of biocides. Overall mortality of the organisms varies but is usually high, often approaching 100 percent. This mortality is thought to be a major factor in reduction of fish stocks in both fresh and saline waters.
Still a further disadvantage of the open-cooling systems is associated with impingement, which is the process whereby larger fish and invertebrates are sucked against the intake screens of a powerplant or forced against the sea floor. The water velocity prevents them from getting off the screens and they remain there until the screens are backwashed. Impinged fish and invertebrates are often killed.
Also, facilities situated on saline waters periodically use biocides, such as chlorine, to control algae, which detrimentally affect organism growth. While much work has been done researching the effects of powerplants on aquatic biota, and numerous intake systems tested, the impacts still remain very much a problem.
The problems are so prevalent that regulatory agencies usually specify an alternate cooling system, such as cooling towers, even though these lessen the thermal efficiency of the powerplant or industrial facility. One such alternative cooling system for a power generation plant 10 is diagrammatically illustrated in FIG. 1 and, in principle, operates by directing steam 12 to a turbine 24 actuating its generator 14, which spins at high velocity generating electricity that is transmitted in the electricity grid 16. Since, as is well known, condensing improves turbine efficiency, power generation plants have at least one cooling tower 18 providing the power plant with a cooling medium, such as cold water typically delivered from a natural water reservoir for efficient operation of a condenser 20. The cooling system, as described immediately above, may be cost inefficient and may have the same problems as the traditional cooling system.
A need therefore exists for a method and system for providing a cooling medium to industrial facilities that retains the advantage of ambient water cooling while minimizing or even completely eliminating all adverse environmental impacts.